Polyethyleneimine-Supported Triphenylphosphine and Its Use as a Highly Loaded Bifunctional Polymeric Reagent in Chromatography-Free One-Pot Wittig Reactions
作者:Patrick Toy、Xuanshu Xia
DOI:10.1055/s-0034-1380810
日期:——
rted triphenylphosphine reagent has been synthesized and used as a highly loaded bifunctional homogeneous reagent in a range of one-potWittigreactions that afforded high yields of the desired products after simple purification procedures. The approach also served efficiently in tandem reaction sequences involving a one-potWittigreaction followed by conjugate reduction of the newly formed alkene
Acyclic Stereoselection in the Ortho Ester Claisen Rearrangement
作者:G. William Daub、James P. Edwards、Carol R. Okada、Jana Westran Allen、Claudia Tata Maxey、Matthew S. Wells、Alexandra S. Goldstein、Michael J. Dibley、Clarence J. Wang、Daniel P. Ostercamp、Steven Chung、Paula Shanklin Cunningham、Martin A. Berliner
DOI:10.1021/jo9614250
日期:1997.4.1
The ortho ester Claisen rearrangement of trisubstituted allylicalcohols exhibits significant levels of diastereoselection. In E allylicalcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Zallylicalcohols, the 1,3-diaxial interaction develops in the transition state leading to